1. Field of the Invention
The present invention relates to digital cameras capable of setting special shooting modes for shooting a plurality of images to be synthesized to form one image, such as a panorama shooting mode.
2. Description of Related Art
Conventionally, a digital camera capable of setting a panorama shooting mode has been known and FIG. 4 illustrates a structure of this kind of digital camera. This digital camera has a microcomputer 21. An operation unit 23 which has a plurality of buttons including a shutter button, an LCD 24 for displaying an image obtained by shooting, and a strobe device 25 are connected to the microcomputer 21. An ASIC (Application Specific Integrated Circuit) 22 having a CPU mounted thereon is connected to the microcomputer 21, the LCD 24, and the strobe device 25. An SDRAM 26 for temporarily storing image data, a shooting lens drive circuit 27, a CCD 28, a voice IC 29 and a card slot 30 of a memory card (not shown) are connected to the ASIC 22. Also, this digital camera includes an electrical battery 31 serving as a power source for the microcomputer 21, the ASIC 22, the LCD 24, the strobe device 25, the SDRAM 26, the lens drive circuit 27, the CCD 28, the voice IC 29 and the card slot 30 described above.
The microcomputer 21 described above receives an operation signal from the operation unit 23 and notifies the ASIC 22 in accordance with the operation signal as well as controlling electrical power supply from the electrical battery 31 to the microcomputer 21, the ASIC 22, the LCD 24, the strobe device 25, the SDRAM 26, the lens drive circuit 27, the CCD 28, the voice IC 29 and the card slot 30 that are comprising the camera, and charge of the strobe device 25. The ASIC 22 receives the notice from the microcomputer 21 and controls the operation of the LCD 24, the strobe device 25, the SDRAM 26, the lens drive circuit 27, the CCD 28, the voice IC 29 and the card slot 30.
In the digital camera described above, in a state where the panorama shooting mode is set, every time a user depresses the shutter button of the operation unit 23, the microcomputer 21 notifies the ASIC 22 of the depression and then image signals for one frame are loaded to the ASIC 22 from the CCD 28 to be converted into digital image data, and the image data is further subject to a predetermined signal processing and then stored in the SDRAM 26. Here, in the case that an AF (Auto Focus) function or an AE (Auto Exposure) function is set to ON, a shooting condition such as a focus distance, an exposure, and a light exposure time set for shooting a first image in the panorama mode is applied to shooting the subsequent images.
Then, when the panorama synthesis operation to the operation unit 23 is conducted by a user, one composite image is formed by synthesizing image data for a plurality of frames stored in the SDRAM 26 in the shooting operation described above, and then the image data of the formed composite image is recorded in the memory card. Here, the composite image can be formed not only on the digital camera, but also on a personal computer. In such a case, the image data for a plurality of frames obtained by shooting is recorded in the memory card without being synthesized, and then the image data for a plurality of frames is loaded into a personal computer from the memory card to be synthesized on the personal computer.
In the conventional digital camera described above, in the case that the remaining battery level is below a predetermined threshold level after a strobe shooting, during the strobe device is being charged, a temporary OFF mode is set, in which the electrical power supply to the components other than the microcomputer 21 and the strobe device 25 stops in order to save the power consumption.
FIG. 5 illustrates a control process executed by the microcomputer 21. First, in step S31, the microcomputer 21 monitors the shutter button to determine whether or not the shutter button is depressed. When it determines NO, it terminates the process. In contrast, when it determines YES, it notifies the ASIC 22 of the depression of the shutter button to make the ASIC 22 execute the shooting operation in step S32. After that, in step S33, it determines whether or not a strobe shooting is conducted, and when it determines NO, it terminates the process.
When the strobe shooting is conducted, it determines YES in step S33 and further determines whether or not the remaining battery level is below a predetermined threshold level Th in step S34. When it determines YES, it sets the temporary OFF mode in step S35, and then the process proceeds to step S36. When it determines NO in step S34, the process proceeds to step S36, bypassing step S35.
In step S36, it starts the charge of the strobe device and then it determines whether or not the strobe device is fully charged in step S37. When it determines NO, it repeats the process of step S37 until the strobe device is fully charged and it determines YES in step S37. Once it determines YES in step S37, it terminates the charge of the strobe device in step S38. Subsequently in step S39, it determines whether or not the temporary OFF mode is set and when it determines NO, it terminates the process. When it determines YES, it cancels the temporary OFF mode setting in step S40 and then terminates the process.
With the process described above, in the case that the remaining battery level is below the predetermined threshold level Th after the strobe shooting is conducted, the temporary OFF mode is set during the charge of the strobe device 25.
Thus, even if the conventional digital camera is capable of strobe shooting in a panorama mode, with this camera, when the remaining battery level falls below the predetermined threshold level during shooting a plurality of images to be synthesized to form one image, the temporary OFF mode would be set and therefore the power source of the ASIC 22 would be set to OFF. Therefore, it will be problematic because the same shooting condition cannot be maintained. In addition, the power source of the SDRAM 26 would also be set to OFF, and therefore, it will be also problematic because the image data stored in the SDRAM 26 can be deleted.
Accordingly, the conventional digital camera is designed so that the strobe shooting cannot be conducted in a state where the panorama shooting mode is set.